Surgical probe for locating foreign metal particles in body tissue



June 8, 1943. s. BERMAN 2,321,355

SURGICAL PROBE FOR LOCATING FOREIGN METAL PARTICLES IN BODY TISSUE FiledJan. 15, 1942 2 Sheets-Sheet l INVEN TOR. .fiwrz/z 52/9109.

y wafi. 3M

June 8, 1943. s, BERMAN 2,321,355

SURGICAL PROBE FOR LOCATING FOREIGN METAL PARTICLES IN BODY TISSUE FiledJan. 15, 1942 2 Sheets-Sheet 2 i l L Z2 JNVENTOR.

ATZ'OMI;

Patented June 8, 1943 UNITED STATES PATENT pg OFFICE SURGICAL PROBE FORLOCATING FOR- EIGN METAL PARTICLES IN BODY TISSUE Samuel Barman,Richmond Hill, N. Y., assignor to Waugh Equipment Company, New York, N.Y.,

a corporation of Maine Application January 15, 1942, Serial No. 426,8519 Claims. (Cl. 177-311) My invention relates generally to devices foreasily, quickly, and completely sterilized by any locating hiddenforeign metallic particles in body of the usual methods used such asheating, or

ssue. More particularly, it relates to a surby steam, or by immersion inor other applicagical probe, which in conjunction with auxiliary tion ofsterilizing agents. equipment which I employ is capable of detect- Ihave also sought to devise a probe as readily ing and indicating thelocation of very small usable as any operative tool or instrument whichmetallic fragments in such tissue. can be readily grasped andconveniently held by Location of foreign substances in body tissuethesurgeon, which is of small cross-section and is now accomplishedprimarily by the X-ray. so formed that it can readily be inserted into oever, the use of X-ray apparatus for the 10 relatively small incisionscr wounds to facilitate purpose is of limited application because itwill the quick location of the foreign metallic parnot always indicatethe position of extremely ticle, and which can be readily fitted with asmall foreign metallic particles with suflicient sterile covering foritself and the cable as a furaccuracy to permit their removal bysurgery. ther sanitary precaution. Furthermore, use of X-ray equipmentfor location When I speak of body tissue, I have in mind, of suchparticles during the actual operation is primarily, human tissue, but itis obvious that extremely dimcult and often impossible This theveterinarian will find much use for-my de limitation has been found fromexperience to be vice in the treatment of injured animals. Other veryundesirable, as sometimes, a number of ex uses for my probe and thecompact auxiliary plorations within the affected tissue are requiredequipment which I have devised will readily sugto find the particle.Such repeated probings gest themselves. mutilate the tissue even underthe best opera- For a better understanding of the invention, tivepractice, and are therefore to be avoided if reference may be had to theaccompanying dra possible My locator can be used during the ings inwhich actual removal operation and because of its great- Fig. 1 is ablock diagram showing how my er accuracy in locating particles, it makesposprobe is associated with the other elements which sible speedieriemoval thereof and thus provides I employ for location of foreignmetallic particles the surgeon with a valuable instrument not hereinbody tissue. tofore available. Fig. 2 is a cross-sectional view of myprobe to hile my locator was developed primarilyto indicate themechanical construction.

be useful in cases involving accidental lodgement Fig. 3 is a sectionalview on line 3-4 of Fig. 2. of metallic particles in body tissue,particularly Fig. 4 is a sectional view on line 4-4 of Fig. 2. inindustrial accidents, it has fortuitously been Fig. 5 is a schematicrepresentation of the electested under actual war conditions at PearlHartrical elements of the probe. bor, where, I am told it supplanted theX-ray to Fig. 6 is a schematic representation of the eleca great extent,resulting in speedier and less trical elements of the balancing means,the excostly position diagnosis. Some of the present citing source, theamplifier, and the indicator day limitations of the X-ray are therelatively Fig. 7 is a schematic representation of a variahigh cost ofthe plates used. and the time and tion of my arrangement showing how myprobe the expert technique necessary to obtain and 40 can be usedwithasingle winding. interpret them These objectionable features are Asillustrated in the drawings and particularly eliminated to aconsiderable degree by use of my in Fig. 1, the locator includes aprobe, generally device in the location of such foreign metallicdesignated i0, connected by a multi-conductor particles in body tissue.cable ii to a balancing unit l2, a source of ex- To meet the peculiarconditions under which citing current l3 for the probe in and thebalsuch metallic fragments, often of very small size, ancing unit I2, avacuum tube amplifier N are found in such tissue. I have sought toproand an indicating means i5 The internal coiiduce a device ofextremely high sensitivity of struction of the preferred form of probein s perception so that such small particles may be shown in Figs 2, 3,and 4 and the electrical cir as readily found as larger ones. I havealso cuits for the probe and associated equipment are the high sanitaryrequirements of modern medicine, and, particularly, the fact will beused in open wounds and specially made incisions. I have thereforedesigned my probe so that it is capable of being shown in Fig. 6.

In the embodiment shown, the vacuum tube amplifier I4 is of conventionalhigh gain type for the two windings used in this bodiment, there will beno appreciable input to put of the amplifier 'such a core 20 forexplain. The leads from and the indicating means which I employ consistsof a conventional direct current meter with a bridge rectifier tomeasure the amplitude of the amplifier output. These featuresaccordingly require no detailed description.

The probe ll contains at least one winding, and for more usefulsensitivity, two windings. When suitably energized by an exciting sourceII, as by an alternating current of suitable voltage and frequency. afield will be set up about the probe It]. When the voltage in the probewinding or windings is suitably balanced, asby the means employed in thebalancing unit l2 preferred emthe vacuum tube amplifier I4, and theindicating means I! will operate at a reference level. This referencelevel may be fixed at the zero point or at any other desired point onthe meter scale by a suitable counterbalancing means. I obtain thisresult in practice by introducing to the meter a direct current ofopposite polarity and of sufficient magnitude to give the desiredreference level.

When the probe I is brought into the vicinity of a metallic particle,the reaction of the metallic particle with the field causes analteration in the character of the field varying with the distance ofthe probe from the particle and the mass and the shape of the particle.Ihis causes one or more changes in voltage, current, or phase in theprobe winding or windings and since the original balance is thusdisturbed, there occurs 'a further change in voltage across the input ofthe amplifier, which is measurable across the outll by. any of the usualindisuch as the meter to which I The indicating means will show eatingmeans, have referred.

' the current filament winding of the filament transformer of theamplifier H. I prefer to use a low voltage because of the lessenedpossibilityof insulation breakdown or by-pass, when the probe is in use.and I thereby reduce the risk of consequent accidental shock to thepatient. The frequency of is not particularlycritical, except that thedesign is influenced by increasing frequency a value above the referencelevel proportionate to the distance of'the metallic particle from theprobe, and also proportionate to the shape and The needle deflectionwill mass of the particle. accordingly increase as the probe is broughtnearer to the metallic particle, and decrease as the probe is drawn awayfrom it, so that the location of the particle may be determined.

The probe contains at least one winding. 2|, preferably wound about acore 20 of magnetically susceptible material, such as soft iron, forlower frequencies, such as I use in this instance. Preferably I make useof two windings 2| and 22 on greater sensitivity. I also include a thirdwinding 23, which I term a phasin winding, the purpose of which I shallpresently these three windings terminate on a terminal block Hi, towhich is attached the multi-conductor cable H, The cable ll serves toconnect the probe to the balancing unit 12, the exciting source ii, theamplifier I4, and the indicating means l5.

, The'balancing unit is an electrical counterpart of the probe unit, andwill therefore have the same number of windings as the probe. In theconstruction being described, the balancing unit contains three windings3 l, 32, and 33 corresponding, respectively, to windings 2t, 22, and 23of the probe and wound on a core member-30 which correspondsmechanically and electrically to probe core 20. Corresponding windings2| and 3| are treated as primaries of identical transformers, and areconnected in series to the exciting current source 13.

In the use of the apparatus described, I employ a low voltage, lowfrequency source of al- I may obtain from a ternating current, whichconsiderations, such as, for instance, in the elimination of magneticcores. I have preferred to develop this embodiment on the basis of usinga low frequency alternating current because such a current is almostuniversally obtainable without difliculty, and its use simplifiesconstructional details.

If the only current available is direct current. a suitable excitingcurrent can be obtained by the use of a local oscillator in conjunctionwith the amplifier, or by using an appropriate inverter. A vibrator ormotor driven interrupter may also be employed to obtain an intermittentcurrent for use as the energizing source I3 for the probe windings. Itherefore do not wish to be limited to the type of current or thefrequency of the current that produces the field surrounding my probe.-

Corresponding windings 22 and 32 of the probe and balancing unit aretreated as secondaries of identical transformers, and upon applicationof the energizing source .13 to the primaries 2| and 3|, a voltage willbe induced in each secondary. However, windings 22 and 32, whileconnected in series, are in opposition and degrees out of phase, so thatthere is substantially a complete elimination of the induced voltages.No appreciable current will therefore flow in the load, which is theinput resistance of the amplifier connected in series with thesecondarie 22 and 32.

From the foregoing, it will be apparent that as soon as the windings areenergized, a field will be set up about the probe, but while that fieldis undisturbed, no appreciable current will fiow in the input circuit ofthe amplifier. However, the presence of a metal within the range of theprobe field will alter the character of the field, so that theoriginalbalance upset, and the degree of unbalance, which depends uponthe distance of the probe from the metal and the shape and mass of themetal,

former, and Ishunt such winding with a load.

which may be either resistive, as indicated-at l7 and I8, or capacitiveand is variable, so that I can vary the load upon the particulartransformer at will. This arrangement permits me to alter the phase ofthe inducedvoltage, andto a lesser degree, the amplitude of the inducedvoltage in the particular secondary, as I find necessary. Although onlyone such third winding so loaded is required on either of thetransformers for the specified purpose, I prefer, for greater ease ofadjustment, to include such a winding with each transformer. variableloads to balance the opposing voltages in the secondaries, and then Imeasure the value of one and replace it with a fixed resistor of suchwill be- I adjust these when the 1 value.

. currents react with ,|2, and an value that the balanced condition isobtained resistor is set for its mean encountered in practice can bereadily overcome.

The third winding with its variable load may be referred to as a phasecontrol and it is used to determine the nature of the metallic particle.since ferrous and non-ferrous metals have different effects upon theprobe field. A particle of ferrous metal within the range of the fielddecreases the reluctance of the magnetic circuit. permitting a largernumber of flux linkages through the probe winding or windings and thuscreating a measurable voltage difference. A particle of non-ferrousmetal within the range of the field has eddy currents induced in it andthese the field to produce partial demagnetization, as well as phaseshift, so that a measurable voltage diiference'results. By suitableadjustment of the variable phasing control I! or IE. it is possible toadjust for maximum sensitivity for the particular suspected metal.

The location 01' the particle is made by expioring along cross lines tofix its position by intersection. I find it desirable to attach to thetip of the probe a marker means, which may be removable, if desired, sothat the proper point of incision may be indicated on the skin surface.The marker may then be detached for further exploration in an incisionor wound.

In the modified construction shown in Fig. 7, there is only one windingon the probe and a or not, The probe winding, designated 2| in Fig. 6,is connected in series with an external balancing winding 3|, serving asexciting current is l3 through the windings 2| and 3|. The amplifierinput is taken from the Junction of windings 2| and 3| and from a pointof corresponding potential difference, which is obtained bya'potentlometer l9 connected across the source ii of exciting current.By adjusting the potentiometer. any desired reference level onindicating means l can be obtained. As the self-induced voltages in thetwo windings may be out of phase with one a another, a phasing meanssimilar to that already described is employed to obtain further balance.

The probe, as illustrated in Figs. 2, 3, and 4. includes a shell 40 ofrelatively small cross-section and smooth outersurface without sharpedges, as shown. The shell contains the core element 20, the severalwindings, the terminal block I6. and the end of the cable. The shell ispreferably of non-magnetic material, and brass. protected againstcorrosion as by chromium plating, enameling. or like treatment, isatisfactory, since it may be subjected to the usual sterilizationtreatment without damage. Otherrnaterials, however,

- may be employed for the shell. such as plastics of appropriatecharacteristics. The shell is of de creasing diameter toward its freeend, so that it can be readily inserted into anincision or other orificefor exploration and it i sufficiently long to provide a handle portionwhich may be easily grasped by the surgeon.

A cap 42 is mounted on the rear end of shell 40 to close it and hold thecore in place and the cable enters the shell through an aperture in thecap. The shell 40 and cap 42 are threaded together. as indicated at 4|,and the cap is provided with an annular recess 43 which may receivefastening means for holding in place a permeability and this sterilesleeve for probe III or cable II. when such a sleeve is used. I

The core 20 is relatively long and conforms generally to the interiorconformation of shell 40. The core has an end portion upon whichwindings 2|, 22, and 23 are wound and it also has a central hollowportion in which a terminal block I6 is mounted. The internal diameterof the shell is slightly greater than the external diameter of thewindings and the hollow portion of the core, as illustrated. so that theshell may be sprung toa considerable degree while in use withoutapplying a bending force to the core either directly or through thewindings. Bending of the core would result in a change in its wouldupset the balance of the instrument and introduce errors in indication.Such errors are avoided by providing the clearance between the shell andthe windings and the core of the windings as described, and also bytapering and thereby stiffening the end portion of the core on which thewindings are mounted.

Windows 50 are provided in the core member 20 so that the terminal blockis readily accessible for soldering the leads from the windings when theshell is removed. Openings 52 are formed in the core beyond the windingsand lead from the outside of the core to the central hollow space.Bushings 44 of insulating material are mounted in openings 52 andthrough these bushings are drawn the leads from the windings to fastenthem to the terminals of terminal block l6. The block is held in placein core member 20 by means of three small projections lia which fit intocorresponding openings 5| in core member 20., The windings 2|, 22, and23 are placed on the forward part of core member 20 between twoinsulating Washers 45 and 46, and the rear washer 4| has openings 41through which the leads to the The openings 41 are aligned with thebushings 44 through which the lead wires also pass. The washers 45 and46 also serve to hold the internal unit of my probe in position withinthe shell.

More or less variation of the exact details of construction ispermissible without departing from the spirit of my invention. I desiretherefore not to be limited to the exact form of con- I hereby claimLetters Patent:

as new and desire to secure by 1. A surgical instrument which comprisesav shell having an elongated portion of the size and shape of a surgicalprobe, said portion having a closed end and a smooth outer surface, acore extending longitudinally within said portion of the shell, aprimary and secondary winding in inductive relation on the core, saidwindings having their axes extending longitudinally of said ing theiraxes extending longitudinally of said portion of the shell, meanssupporting the core and windings within said portion of the shell inspaced relation thereto, and a cable entering the shell and containingconductors connected to the terminals of the windings. '3. A surgicalinstrument which comprises an elongated shell of the size and shape of asurgical probe, said shell having a closed end and a smooth outersurface, a core extending longitudinally within said portion oftheshell, a primary and a secondary winding in inductive relation on thecore, said windings having their axes extending longitudinally of saidportion of the shell, means supporting the core and windings within theshell, removable means for closing the other end of the shell, and acable entering the shell through said removable means and containingconductors connected to the terminals of the windings.

4. A surgical instrument which comprises a shell having an elongatedportion of the size and shape of a surgical probe, said portion having aclosed end and a smooth outer surface, a core extending longitudinallywithin said portion of the shell, a primary and a secondary winding ininductive relation on the core, said windings having their axesextending longitudinally of said portion of the shell, means supportingthe core and windings within. said portion of the shell, a

' terminal block within the shell having terminals connected to theterminals of the windings, and a cable entering the shell and containingconductors connected to the terminals on minal block.

5. A surgical instrument which comprises a shell having an elongatedportion of the size and shape of a surgical probe, said portion taperingto a'closed end and having a smooth outer surface, a core extendinglongitudinally within said portion of the shell and having a tapercorresponding generally to that of said portion of the shell, a primaryand a secondary winding in inductive relation on the core, said windingshaving their axes extending longitudinally of said portion of-the shell,means supporting the core and windings within said portion of the shell,and a cable entering the shell and containing conductors connected tothe terminals of the windings.

6. A surgical instrument which comprises a shell having an elongatedportion of the size and shape of a surgical probe, said portion having aclosed end and a smooth outer surface, a core extending longitudinallywithin said portion of the shell and having a longitudinally extendingpassageway therein, a primary and a secondary winding in inductiverelation on the core, said windings having their axes extendinglongitudinally of said portion of the shell, an opening in the coreleading from said passageway to the space within said portion of theshell, the leads the terfrom the windings passing through said openinginto the passageway within the core, means supporting the core andwindings within said portion of the shell, and a cable entering theshell and containing conductors connected to the winding leads. I

7. A surgical instrument which comprises a shell having an elongatedportion of the size and shape of a surgical probe, said portion having aclosed end and a smooth outer surface, a core extending longitudinallywithin said portion of the shell, 2. portion of said core being hollow,a primary and a secondary winding in inductive relation on the core,said windings having their axes extending longitudinally of said portionof the shell, means supporting the core and windings within said portionof the shell, a terminal block within the hollow portion of the corehaving terminals thereon, an 'opening in the core leading from theoutside thereof to the space therewithin, the leads from the windingspassing through said opening and being connected to the terminals on theterminal block, and a cable entering the shell and containing conductorsconnected to the terminals on the terminal block. 1 8. A surgicalinstrument which comprises a shell having an elongated portion of thesize and shape of a surgical probe, said portion having a closed end anda smooth outer surface, a core extending longitudinally within saidportion-of the shell, a primary and a secondary winding in inductiverelation on the core, a third winding on the core, said windingshavingtheir axes extending longitudinally of said, portion of the shell, meanssupporting the core and windings within said portion of the shell, acable entering the shell and having conductors connected to theterminals of the respective windings, and a lead connected through theconductors across the terminals of the third winding.

9. A surgical instrument which comprises a shell having an elongatedportion of the size and shape of a surgical probe, said portion having aclosed end and a smooth outer surface, a core extending longitudinallywithin said portion of the shell, a primary and a secondary winding ininductive relation on the core, a third winding on the core, saidwindings having their axes extending longitudinally of said portion ofthe shell, means supporting the core and windings within said portion ofthe shell, a second core outside of said portion of the shell, a primaryand a second ary winding in inductive relation on said second core, theprimaries of the two sets being connected in series and the secondariesof the two sets being connected in series but in opposition, a thirdwinding on the second core, and loads across the third windings of thetwo sets, at least one of the loads being variable.

SAMUEL BERMAN.

